SOFT-TISSUE STUDIES WITH 805 NM DIODE-LASER RADIATION - THERMAL EFFECTS WITH CONTACT TIPS AND COMPARISON WITH EFFECTS OF 1064 NM ND-YAG LASER-RADIATION

This study compares the perioperative depths of thermal coagulation, c harring, and incision in rabbit liver, internal anterior abdominal wal l skeletal muscle, and abdominal skin and in swine liver and abdominal skin obtained with 805 nm diode laser and 1,064 nm Nd:YAG laser radia tion using 300-mum-diameter conical-tip and 1,200-mum-diameter spheric al-tip contact fibers by hand. Additionally, the total depth of tissue necrosis surrounding incisions made with both lasers and contact tips is determined 48 hours postoperatively in the three tissues, and heal ing of the liver and abdominal wall muscle 21 and 35 days postoperativ ely is assessed histologically. Perioperatively determined charring, c oagulation, and incision depth obtained in all tissues with either 805 nm or 1,064 nm laser radiation were sensibly equivalent at equal lase r power values for each of the two contact tip shapes tested. At equal laser power values, coagulation depths obtained in rabbit abdominal s kin using the 300-mum-diameter conical tip differed significantly (P l ess-than-or-equal-to 0.01) from those values obtained with the 1,200-m um-diameter spherical tip. Incision depths obtained with the two diffe rent contact tip shapes at equal laser power settings in the different tissues studied differed in a few instances with no apparent pattern relating to tissue type or laser power. Depth of incisions obtained wi th both laser and tip types increases in the range of 6-12 w, but plat eaus in the range 12-18 w in the tissues studied. Incisions obtained w ith both diode and Nd:YAG laser contact were essentially hemostatic, w ith self-limiting oozing at most. Tissue necrosis examined at 48 hours showed invasion of inflammatory cells in liver, abdominal skeletal mu scle, and skin; 21 and 35 days postoperatively, histology samples of l iver and skeletal muscle showed healing with normal fibrous tissue dep osition. Results of this study support the essential equivalency of ti ssue thermal effects obtained with the 805 nm diode and Nd:YAG lasers in the contact mode and support the use of the diode laser as an alter native medical laser. (C) 1993 Wiley-Liss, Inc.